2 4 CONTEMPORARY SCIENCE 



experimentally from the X-ray spectrum so that we are 

 not dependent upon the periodic table for our knowledge 

 of these numbers. 



Bohr, Sommerfeld and others have developed an exten- 

 sive and very successful theory of spectra upon the hypo- 

 thesis that the electrons in atoms are in rapid rotation in 

 plane orbits about the nucleus in much the same way as 

 the planets revolve around the sun. Stark, Parson, and 

 G. N. Lewis on the other hand, starting from chemical 

 evidence, have assumed that the electrons are stationary 

 in position. It should be noted that Bohr's theory has had 

 its greatest success when applied to atoms or ions contain- 

 ing only one electron and that it seems incapable of ex- 

 plaining the chemical or ordinary physical properties of 

 even such simple elements as lithium, carbon, or neon. 



The two theories can, however, be reconciled if we con- 

 sider that the electrons, as a result of forces which they 

 exert on one another, rotate about certain definite posi- 

 tions in the atom which are distributed symmetrically in 

 three dimensions. Thus for atoms containing only a 

 single electron the chemical theory is in agreement with 

 Bohr's theory. But for an atom such as neon the eight 

 electrons in the outside layer would revolve around posi- 

 tions which are located about the nucleus in the same 

 way that the eight corners of a cube are arranged about 

 the center of the cube. This structure is not inconsistent 

 with those parts of Bohr's theory which have received ex- 

 perimental confirmation. In fact, Born and Lande, 1 

 starting from Bohr's theory and without knowledge of 

 Lewis' work, arrived at exactly this conception of the 

 structure of atoms (i.e., the cubic atom) from a study of 

 the compressibility of the salts of the alkali metals. 



The atomic numbers and the properties of the inert 

 gases furnish us with a clue to the arrangement of the 

 electrons within atoms. The low boiling point, the high 



. d. phys. Ges., 20 (1918), 210. 



